Saturable transformer



Feb. 19, 1952 w. J. HOLT, JR 2,586,657

SATURABLE TRANSFORMER Filed Aug. 24, 1948 [N VEN TOR.

Patented F eb. 19, 1952 SATURABLE TRANSFORMER William J. Holt, Jr., Garland, Tex., assignor to Varo Mfg. 00., Inc., Garland, Tex., a corporation of Texas Application August 24, 1948, Serial No. 45,932

This invention relates to that class of transformers known as variable voltage transformers and has a special reference to such transformers when the output voltage of the transformer can be varied with respect to the input voltage by changing the magnetic saturation in one leg of the transformer by means of a D. C. winding.

One of the objects of the invention is to provide an electrical means whereby the output A. C. voltage of the secondary of the transformer can be maintained at a constant value when the secondary has a fixed load imposed on it and the primary A. C. voltage is changing. Another object is to provide an electrical means of maintaining a constant voltage output in the secondary of a transformer as various load values are applied to the secondary and with a constant A. C. voltage on the primary. Still another object is to provide a means of electrically controlling and maintaining a constant A. C. voltage in the secondary of a transformer as various loads are applied to the secondary and/or with the A. C. primary voltage varying at the same time. A fourth object of the invention is to provide an electrical means of varying the secondary A. C. voltage of a transformer with a fixed or variable A. C. input voltage on the primary. A fifth object is to provide a means by which the output voltage might be modulated by another frequency different from that of the primary and secondary.

,The construction and operation of this invention is explained by reference to the accompanying drawing:

The saturable transformer shown in the drawing is composed of four cores 3, 4, and 6, two similar primary windings I and 2, one saturable winding I and two similar secondary windings 8 and 9. The two iron cores 3 and 4 are the same in cross sectional area, core length and iron characteristics. The two iron cores 5 and l B are also similar in cross sectional area, core length and iron characteristics. Variations in the types of iron and core construction may. be made without effecting the electrical operation. Square laminated cores may be used as well as round laminated cores, as may also the wound circular or elliptical cores.

In the transformer, I is a primary winding and upon being energized with an A. C. voltage, sets up in cores 3 and 5 an A. C. flux that cuts the secondary winding 8 and the saturating winding I. At the same time winding I is being energized, winding 2 is energized by virtue of the fact that it is connected in parallel with winding I. Winding 2 on being energized, sets up in cores 4 and I5 5 Claims. (Cl. 323-56) sets out the use of four separate cores.

an A. C. flux that cuts the secondary winding 3 and the saturating winding I. Primary windings I and 2 are so wound that the alternating flux in the portion of core 3 encircled by control winding I is opposite and. equal to the alternating flux in the portion of core 4 encircled by control winding I. Since the alternating fiux in core 3 is equal and opposite to the alternating flux in core 4, the sum of the alternating fluxes in the portions of cores 3 and 4 encircled by coil I is substantially zero and little or no alternating current is induced in coil I by the alternating fluxes in cores 3 and 4. Since no alternating current is induced in control winding I, it is possible to saturate cores 3 and 4 with direct current in control winding I. The current for the saturating winding 1 may be derived from many kinds of D. C. sources, one being a battery III, as shown and the amount of current desired for saturation determined by the variable resistor II as shown. With the cores 3 and 4 saturated by the D. C. current in the saturating winding I most of the A. C. flux generated in the primary winding I flows through the outside core 5 and sets up in the secondary winding 8 an A. C. voltage, proportional to the value of saturation in the D. C. winding 1. In the same way most of the A. C. flux generated by winding 2 flows through the core Ii and sets up in the secondary winding 9 an A. C. voltage that is also proportional to the D. C. saturation in winding I. Thus by varying the saturation in cores 3 and 4 by D. C. current in the saturating winding I, the output voltage of the secondary windings 8 and 9, connected either in series or parallel, can be varied directly or indirectly with respect to the input A. C. voltage of the primaries I and 2.

Itshould be understood that this description This is done for clarity, but should not limit the scope of my invention. Cores may be built in one, two, three or four parts and still fulfill all the requirements as set forth in the claims below.

I claim:

1. In combination: a magnetic core means comprising two pairs of closed flux paths; a first primary winding for inducing an alternating flux in one pair of said closedflux paths; a secondary primary winding for inducing an alternating flux in the other pair of closed flux paths, said primary windings being connected in parallel; a control'winding for simultaneously and equally varying the saturation of one closed flux path of each of said pairs of closed flux paths, the fluxes in said last mentioned closed flux paths primary winding operatively associated with the flux paths of one of said pairs of closed flux paths; a second primary winding operatively associated the flux paths of the other of said pairs of closed flux paths, said primary windings being connected in parallel and inducing alternating fluxes in said pairs of closed flux paths; a con trol winding operatively associated with one flux path 01 each pair 0! closed paths for simultaneously and equally varying the saturation of the flux paths with which said control winding is operatively associated, the fluxes in said last mentioned flux paths flowing in opposite directions with respect to said control winding; and a secondary winding on each one of said flux paths not variably saturated by said control winding, said secondary windings being connected in parallel.

3. In combination: a magnetic core comprising four closed flux paths; a first primary winding connecting the first and second of said closed flux paths; asecondprimary winding connecting the third and fourth of said closed flux paths, said primary windings being connected in parallel and adapted to be energized by alternating current for inducing alternating fluxes in said closed flux paths; a control winding connecting said second and third flux paths and adapted to be energized by direct current for varying the saturation of said second and third fiux paths, the alternating fluxes in said second and third flux paths flowing in opposite directions with respect to said control winding; a first secondary winding on said first flux path; and a second secondary winding on said first fiux path, the alternating fluxes induced in said first and fourth flux paths by said primary windings inducing an alternating current in said secondary windings, said secondary windings being connected in parallel.

4. In combination: a magnetic core means comprising four closed flux paths; a first primary winding adapted to be energized by alternating current for inducing an alternating flux in the first and second of said closed flux paths; a second primary winding adapted to be energized by alternating current for inducing an alternating flux in the third and fourth of said closed flux paths; 9. control winding connecting said second and third flux paths and adapted to be energized by direct current for varying the saturation of said second and third flux paths, said primary windings being wound to induce alternating fluxes in said second and third flux paths ing adapted to be energized by alternating current for inducing alternating fluxes in the third and fourth of said flux paths; control means for variably saturating said second and third flux paths; and secondary windings operatively associated with said first and fourth flux paths, said alternating fluxes inducing an alternating current in said secondary windings.

WM. J. HOLT, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 720,884 Burgess Feb. 17, 1903 1,376,978 stoekle Ma 3, 1921 1,661,740 Stoekle Mar. 6, 1928 1,910,381 Dowling May 23, 1933 

